Yes, many conservative leaders have practiced a coarse and divisive politics. But Trump has taken it to a whole new realm.

The rise of Donald Trump has shaken Sen. Jeff Flake, R-Ariz., to his core. At least that’s the conclusion I reached upon reading his new book, publicly available this week.

Flake drew inspiration from Barry Goldwater’s Conscience of a Conservative and gave his book the same title.

More: Conservatives should love the Trump presidency, but he makes it hard

Goldwater’s book, published in 1960, defined conservatism and sought to show how its principles would apply to the issues of that day. It contains the best single-sentence definition of conservatism I’ve ever encountered: “The Conservative looks upon politics as the art of achieving the maximum amount of freedom for individuals that is consistent with the maintenance of the social order.”

Flake, however, doesn’t really seek in his book to do today what Goldwater’s book did in his time. Instead, he really seeks to perform the sort of intellectual hygiene William F. Buckley Jr. used to conduct to rid conservatism of malign elements, which Flake regards Trump and Trumpism as being.

In 1963, Buckley wrote an essay titled “Notes toward an empirical definition of conservatism,” which is the lead item in his anthology, The Jeweler’s Eye.

He mostly defined conservatism by identifying what it was not. Buckley’s essay at that time excluded from conservatism the conspiracy theorists at the John Birch Society, Ayn Rand’s Objectivism, anarchists of the academic variety and atheists who made the destruction of religion a priority.

Flake writes not only to exclude Trump and Trumpism from conservatism, but to define conservatism as in opposition to him and it.

In a section under the rubric “What Would Goldwater Do?” Flake catalogs a litany of Trumpian sins against conservative thought and action, from protectionism, to ducking entitlement reform, to praising dictators and many things in-between.

Flake’s most detailed takedown of Trump is on trade. He provides a masterful explanation of the indispensability of international trade to a country such as the United States and the domestic benefits of it, particularly from NAFTA, which Trump has denounced as the worst trade deal ever. It’s worth a read all on its own.

But it is clear that what most disturbs Flake and made him feel compelled to write this book is the way Trump…